Feathers in furnace: Birds at the risk of urban heat

The first victims of India’s growing heat crisis are often the ones we overlook.

Urban India is noticeably warming, and the mornings are quieter in many built-up neighbourhoods. Scientists now warn that the Urban Heat Island (UHI) effect is intensifying conditions that make cities increasingly difficult for many bird species to survive in.

When temperatures crossed 45°C in parts of Delhi (India Meteorological Department records), rescue centres recorded many cases of dehydrated and collapsing birds like pigeons, parakeets and kites, struggling to find shade or water. Similarly in Ahmedabad, rescuers reported finding many birds weak and dehydrated during sustained heat spells.

What exactly is an Urban Heat Island?

An Urban Heat Island (UHI) forms when concrete, asphalt and built-up areas absorb and retain heat during the day and release it slowly at night, keeping urban centres several degrees warmer than nearby rural regions.

Dense construction, loss of vegetation, and waste heat from vehicles and air conditioners amplify this effect. In Indian metros such as Delhi, Ahmedabad, Bengaluru and Mumbai, UHI intensity commonly ranges from about 2-10°C depending on measurement method, with the hottest surface hotspots sometimes 6-8°C warmer on peak days, according to recent reviews.

This microclimatic heating affects air quality and vegetation and reduces the availability of shade and water that urban wildlife depends on. Birds, being small endotherms with high metabolic rates, are among the first to show stress.

Heat islands reduce bird diversity, as scientific evidence now shows

Recent ecological studies have begun quantifying what rescuers already see on the ground.

In a 2025 study, researchers led by R. Jambhekar mapped Bengaluru’s bird communities against satellite surface-temperature data and found lower abundance in the city’s hotter patches. In short, higher local surface temperatures were associated with reduced bird numbers in those areas.

Similarly, using citizen-reported bird sightings from the Western Ghats, a 2022 study found that rising temperatures and shrinking green cover were changing where birds could survive, with forest-dependent species disappearing first from warmer, human-dominated areas.

A 2023 multi-city study from China reported that stronger surface heat was associated with lower bird species richness and reduced functional diversity in the cities it examined.

Physiologically, high urban temperatures cause dehydration, hyperthermia, and oxidative stress in birds. Behaviourally, many shift activity to dawn or dusk, abandon nests on exposed branches, or shorten their breeding season. Prolonged exposure can even reduce hatching success and chick survival.

In short, urban warming is reshaping the ecological balance of many Indian cities.

Rescue reports tell the same story

The scientific evidence also confirms what wildlife volunteers have been witnessing for years.

In May 2022, international outlets including Reuters and Al Jazeera reported rescuers collecting dehydrated birds during a severe Gujarat heatwave when temperatures reached the mid-40s.

A Times of India report noted that organisations such as Wildlife SOS and the Charity Bird Hospital recorded noticeable increases in heat-related bird admissions during recent summers.

By 2024, similar stories emerged from Mumbai, where wildlife hospitals reported spikes in kite, myna and pigeon rescues during May-June heatwaves (Indian Express, 2024), while People For Animals (PFA), Bengaluru, reported a rise in dehydrated and heat-stressed birds during the same period (Mongabay-India, August 2024).

In May 2025, The Times of India again reported that the Jivdaya Charitable Trust treated about 3,800 birds in Ahmedabad over several weeks of extreme heat.

Volunteer rescuers working in multiple cities reported that where there were trees, there were fewer heat rescues, whereas in treeless commercial zones, more collapsed birds were observed.

Taken together, field reports and urban heat maps suggest that high surface-temperature zones may overlap with neighbourhoods reporting more rescue cases and fewer bird sightings.

Beyond birds: Urban heat disrupts entire ecosystems

The UHI effect doesn’t act alone. It interacts with air pollution, light pollution, and habitat fragmentation to intensify ecological stress. Hotter air reduces moisture retention in trees and lowers insect abundance, depriving birds of prey and nesting cover. Amphibians lose breeding ponds as water evaporates faster, while bats abandon overheated roosts.

Some insectivorous species are reported to even shift activity or distribution toward cooler suburban or peri-urban edges where habitat and food remain available.

The result is biotic homogenisation, i.e., cities becoming dominated by a few heat-resilient species while specialist or migratory birds disappear as reviewed in recent scientific literature.

Urban planning: Where biodiversity meets climate

India’s Smart Cities Mission and urban master plans often address heat mitigation through engineering such as reflective roofs, pavements, or ventilation corridors, but rarely integrate ecological cooling. Yet, green cover and water bodies are among the most effective natural cooling systems.

Remote-sensing and microclimate studies indicate tree-rich urban patches are commonly 1-3°C cooler in air temperature and can be substantially cooler at the surface, depending on canopy density and park size.

In Delhi, areas such as the Ridge and Lodhi Gardens tend to support richer bird life and show milder night-time temperatures compared with nearby built-up zones, according to local studies and citizen observations.

Urban ecologists argue that heat adaptation and biodiversity conservation are inseparable goals. Cooling the city helps both, people and wildlife survive extreme summers which is a win-win in climate policy.

Designing cities that breathe, and shelter life

The science and rescue data point to a simple truth: nature itself is the best coolant.

Cities can reduce UHI and support wildlife through nature-based strategies: 

1. Increase urban canopy cover: Native trees like neem, jamun and banyan lower air temperature by 1–3°C and surface temperature slightly more in shaded zones.

2. Restore ponds and wetlands: Small water bodies act as heat sinks and vital drinking sources for birds and small mammals.

3. Encourage cool roofs and vertical gardens: Reflective paints, green walls and rooftop gardens lower ambient temperatures and offer microhabitats.

4. Create urban biodiversity corridors: Linking parks and water bodies allows species movement, improving resilience to heat.

5. Citizen interventions: Placing water bowls, planting shade trees, and protecting old trees have tangible cooling benefits.

These strategies align with policy measures under India’s National Mission on Sustainable Habitat and contribute to SDG 11 (Sustainable Cities) and SDG 15 (Life on Land), though implementation varies across cities.

A hopeful horizon

As Indian cities expand, urban warming is expected to continue; the key question is how cities adapt to remain livable for people and wildlife alike.

Birds are the most visible messengers of ecological imbalance. Their silence in city mornings is not only a warning, but also a call to action. By integrating biodiversity into urban design, planting native trees, restoring wetlands and mapping urban heat alongside species records, cities can cool themselves naturally. Every shaded park, every rooftop garden, every bowl of water becomes part of a living cooling network.

Saving birds from the heat is, in the end, about saving the soul and sustainability of our cities. 

Sundus Shamsi is a PhD Scholar at the Department of Wildlife Sciences, Aligarh Muslim University

Kaleem Ahmed is Assistant Professor at the Department of Wildlife Sciences, Aligarh Muslim University

Views expressed are the authors’ own and don’t necessarily reflect those of Down To Earth